The term "emission" is used at least with two different meanings in the literature about display devices.
The first and most generic case does reference to the presence of an electroluminiscent or similar phenomenon. These devices generate light from another type of energy, by example LEDs. In this sense, devices that reflect light but don't generate it would be non-emission displays like electrophoretic displays.
The second and most restrictive case does reference to electronic emission, by example: Cathode Ray Tubes (CRT), or Field Emissión Displays (FED) in both cases there are emission of electrons from a cathode or multiples cathodes to a viewing screen, where image is formed.